Thanks Steve for the pictures, something else I have got to do now, is write this!
The brickwork is DAS that has been scribed using dental tools from Squires tools. Also I used a small brass wire brush similar to a suede brush. Every time you do a little bit brush it along the horizontal mortar lines, when you are satisfied with the look of it and you have completed in full (takes several hours/days), it comes down to the painting, I used a selection of artist acrylic colour (Windsor&Newton) -- Cadmium Orange / Cadmium Red / Venetian Red / Raw Sienna / Burnt Sienna.
The book I used was called "Cottage Modelling for Pendon" by Chris Pilton, published by Wild Swan, ISBN0 906867 57 6; that also gives a good list of colours for brick and stone work.
Put dabs of colour onto a palatte, mix and match as you go along, paint stones and bricks randomly as this makes them stand out better, then colour wash with a mortar mix, watered down and wiped off before drying. Hope this helps, if not come back to me.